im trying to get just first paragraph from about page to home page went through some code on internet but didnt help at all

function get_first_paragraph(){
global $post;
$str = wpautop( get_the_content() );
$str = substr( $str, 0, strpos( $str, '</p>' ) + 4 );
$str = strip_tags($str, '<a><strong><em>');
return '<p>' . $str . '</p>';
}
<?php echo get_first_paragraph(); ?>